Filter elements of this kind are readily available on the market in a plurality of designs. Such filter elements, as they are described for example in DE 10 2004 061 078 A1 and EP 0 001 407 B1, are designed to be inserted into a filter housing for the purpose of cleaning dirty fluid, for example in form of a hydraulic medium, through the inserted filter material of the filter element, and to return the cleaned fluid from the filter housing back into the fluid circuit, in particular a hydraulic fluid circuit. If after a plurality of filter cycles the filter material is blocked with dirt to the degree that it is unusable, the filter element is removed from the housing and replaced by a new element.
To increase the filtering surface, the filters are usually made of a star-shaped folded or pleated strip of filter mat, which concentrically surrounds an internal and/or external supporting tube in a circular manner. The filter material with its cross-sectional star-shaped arrangement of filter pleats is able to brace against an internal or external supporting tube depending on flow direction. To that extent, the filtration direction can be reversed so that reverse flushing actions with already cleaned fluid are possible. In his way, a filter material that is clogged with contaminating particles can be cleaned. The filter material as such has a multi-layer mat structure. The respective layer arrangement is dependent on the required filtration task. Nevertheless, layer arrangements are often used that have purely filtering or draining layers that are made from native fibres, glass fibres, metal fibre material and synthetic fibres such as meltblown fibres, carbon fibres and so on. To ensure the secure adherence of the layers to each other, the two cover layers of the filter material can be made from a finely woven synthetic or wire fabric as the respective supporting fabric, which also prevent the washing out of fibre material during operation of the filter element.
The disadvantage of such filter elements, which are on the market in many different forms and designs and which are widely used, for example, in hydraulic systems where hydraulic oil flows through system branches, is that they are often on the market as counterfeit products without guaranteed characteristics and labelling. Furthermore, often low-quality counterfeit products appear on the market that bear the original company logos and manufacturer's details, and thus, obscure the facts and mislead consumers regarding the actual source of the filter element product.
With specified filter characteristics such as differential pressure stability, beta stability, filter fineness in conjunction with purity class, dirt absorption capacity, long-term service characteristics and such, many different hydraulic-related filter tasks can be met if and as long as original filters from reputable manufacturers are used and not low-quality counterfeit products that usually come from low-wage countries and illegally enter the world-wide market.
Due to increased quality requirements, which are also the result of the complexity of modern machines and plants that operate with hydraulic components, it is indispensable that, for the specified filter task, the filter element used is preferably designed specifically for the required filter characteristic. In particular in the instance where the application of the filter element fluid filtration involves a security-related technology, the breakdown or malfunction of the filter element could lead to serious damage of machines and/or injury to persons.
This danger is always present where counterfeit products or technically inferior copies are used that do not come with reliable product information. Due to the illegal use of company details, such as logos and company names, the counterfeit products are erroneously attributed to the original manufacturer, who may then be held accountable by the operator for the damage done to machines and plants caused by the counterfeit products.